In heart surgery that involves cardiac arrest in a patient, a heart-lung machine is used for taking over the functions of respiration and circulation during the cardiac arrest. Further, during the surgery, it is necessary to lower the patient's temperature and maintain the same so that the patient's oxygen consumption should decrease. For this purpose, the heart-lung machine is equipped with a heat exchanger to control the temperature of blood taken out of the patient.
As such a medical-use heat exchanger, a bellows-type heat exchanger, a multi-tubular heat exchanger (see Patent Document 1, for instance), etc., have been known conventionally. Among these, the multi-tubular heat exchanger has a larger area used for heat exchange as compared with the bellows-type heat exchanger with the same device capacity, and hence, it has the advantage of a higher heat exchange ratio as compared with the bellows-type heat exchanger.
Here, an example of the conventional multi-tubular heat exchanger is described specifically with reference to FIGS. 9A to 9C, and 10. FIGS. 9A to 9C show a configuration of a conventional heat exchanger. FIGS. 9A, 9B, and 9C are a top view, a side view, and a front view of the same, respectively.
FIG. 10 is a partially cut-off perspective view illustrating the inside of a housing of the heat exchanger shown in FIGS. 9A to 9C.
As shown in FIGS. 9A to 9C, the conventional heat exchanger includes a plurality of pipes 1 through which cold/hot water flows, a housing 102 for housing the pipes, and sealing members 103a to 103c for sealing blood flowing over surfaces of the plurality of pipes 1. Further, as shown in FIGS. 9A to 9C and 10, the plurality of pipes 1 are arranged in parallel with one another in the housing 102.
Still further, the housing 102 includes an inlet 104 for introducing blood into the housing, and a first outlet 105 for discharging blood out of the housing. The inlet 104 is an inlet of a flow path 108 of blood, while the first outlet 105 is an outlet of the flow path 108 of blood, which will be described later.
Further, as shown in FIG. 10, in the heat exchanger, there are a first sealing member 103a positioned on one of end sides of the plurality of pipes 1, a second sealing member 103b positioned on the other end side of the pipes, and a third sealing member 103c positioned between the first and second sealing members 103a and 103b. The first, second, and third sealing members 103a, 103b, and 103c are involved in the sealing among the pipes 1. The third sealing member 103c is provided so that a gap 7 is provided between the third sealing member 103c and the first sealing member 103a, as well as a gap 7 is provided between the third sealing member 103c and the second sealing member 103b. Further, as shown in FIGS. 9A to 9C, the flow path 108 is formed in the third sealing member 103c so that blood introduced from the inlet 104 into the housing 2 is guided to the first outlet 105. The third sealing member 103c provides a sealing for blood. Further, the housing 102 is provided with second outlets 106 in a manner such that the second outlets 106 communicate with the gaps 7.
Therefore, in the conventional heat exchanger shown in FIGS. 9A to 9C, in the case where, for example, blood leaks due to seal leakage of the third sealing member 103c, the blood having leaked is retained temporarily in the gaps 7, and thereafter is discharged through the second outlets 106 to outside the heat exchanger. In the case where cold/hot water leaks due to seal leakage of the first sealing member 103a or the second sealing member 103b, the cold/hot water having leaked is retained temporarily in the gap 7, and thereafter is discharged through the second outlets 106 to outside the heat exchanger. As a result, according to the heat exchanger shown in FIGS. 9A to 9C, in both the cases where blood leaks and where cold/hot water leaks, the leakage through the sealing can be detected immediately, and further, the occurrence of blood contamination can be prevented.
It should be noted that in FIGS. 9A to 9C, 114 and 115 denote injection holes for filling a material for forming the sealing members, which are provided on the top face of the housing 102, and 116 and 117 denote air vents used upon the filing of the material for forming the sealing members, which are formed on side faces of the housing 102. The injection holes 114 and 115, and the air vents 116 and 117 are described later.
Next, as to a series of principal steps of a process for manufacturing the conventional heat exchanger shown in FIGS. 9A to 9C and 10 are described below, with reference to FIGS. 11 to 14. FIGS. 11A to 11C show pipe groups composing a heat exchange module; FIGS. 11A, 11B, and 11C are a top view, a front view, and a perspective view, respectively. FIGS. 12A, 12B, and 12C are a heat exchange module composed of a plurality of pipes; FIGS. 12A to 12C are a top view, a front view, and a perspective view, respectively. FIG. 13 is a top view illustrating the state in which the housing is attached to a jig so that sealing members are formed. FIG. 14 is a cross-sectional view showing a step for forming the sealing members.
First, as shown in FIGS. 11A to 11C, a pipe group 10 is formed, which includes two or more (nine in the example shown in FIGS. 11A to 11C) pipes 1 arrayed in a row in parallel with one another, and pipe array holding members 9a to 9d, each of which is present in gaps between the pipes and holds the array of the pipes 1. In the pipe group 10, the pipe array holding members 9a to 9d are in a state of being pierced by the pipes 1, whereby the array of the pipes 1 is held. The pipe array holding members 9 are formed in a belt-like shape, and the two or more pipes 1 are arrayed in a row in the lengthwise direction of the belt. Further, four of the pipe array holding members 9 are arranged along the central axes of the pipes 1.
In the example shown in FIGS. 11A to 11C, the pipe group 10 is formed by pouring a resin into a die in which the two or more pipes 1 are arranged so that the pipe array holding members 9a to 9d are formed; that is, the pipe group 10 is formed by insert molding. A plurality of the pipe groups 10 are produced. Further, the pipe array holding members 9a to 9d are provided with a plurality of recessed portions 11.
Next, as shown in FIGS. 12A to 12C, a heat exchange module 12 is formed by stacking a plurality of pipe groups 10. Here, the pipes 1 composing each pipe group 10 are fitted in the recessed portions 11 provided at the pipe array holding members 9a to 9d of the pipe groups adjacent to each other in the vertical direction.
Further, in order to prevent the resin material flowing into the gaps 7 in the step of forming the sealing members by filling a resin material, which will be described later (see FIGS. 13 and 14), the pipe array holding member 9a of each pipe group 10 is brought into close contact with the pipe array holding members 9d of another pipe groups 10 immediately above and below the foregoing group. Likewise, the pipe array holding members 9b, 9c, and 9d of each pipe group 10 are brought into close contact with the pipe array holding members 9c, 9b, and 9a of another pipe groups 10 immediately above and below the foregoing group, respectively. The close contact is achieved by using an adhesive.
Next, the heat exchange module 12 shown in FIGS. 12A to 12C is housed in the housing 102. Here, the heat exchange module 12 is fixed in a state such that portions of the pipe array holding members 9a to 9d of each pipe group 10, which are exposed on surfaces of the heat exchange module 12, adhere to inner surfaces of the housing 102 with use of an adhesive.
Next, as shown in FIG. 13, first, the housing 102 in which the heat exchange module 12 is housed is attached to a jig 118. The jig 118 is composed of a main body plate 118a, and a pair of pressing plates 118b and 118c that sandwich the housing 102 at opening thereof on both the sides thereof. Packings 119 are provided between the pressing plates 118b and 118c and the housing 102.
Further, the jig 118 is configured rotatably around, as the center, an axis that passes through the center of the inlet 104 and the center of the first outlet 105. On the top face of the housing 102, a mask 120 is attached, so that a resin material is prevented from intruding through the inlet 104. The mask 120 is provided with apertures so that the injection holes 114 and 115 are not closed.
Next, as shown in FIG. 14, an injection pot 121 is attached on the top face of the housing 102. The injection pot 121 includes flow paths 124 for guiding a resin material 123 injected into the injection pot 121 to the injection holes 114 and 115. Here, 122 denotes a lid of the injection pot. It should be noted that in FIG. 14, the heat exchange module 12 is shown as viewed from a side thereof.
Further, as shown in FIG. 14, the injection hole 115 shown in the left-side part of the drawing is formed so as to communicate with interstices around the pipes 1 between the opening of the housing on the left side as viewed in the drawing and the outer-side pipe array holding member (9a or 9d) of each pipe group 10 on the left side as viewed in the drawing (hereinafter referred to as “first housing space”). On the other hand, the injection hole 115 shown in the right-side part of the drawing is formed so as to communicate with interstices around the pipes 1 between the opening of the housing on the right side as viewed in the drawing and the outer-side pipe array holding member (9d or 9a) of each pipe group 10 on the right side as viewed in the drawing (hereinafter referred to as “second housing space”).
Further, the injection holes 114 are formed so as to communicate with interstices around the pipes 1 between the two inner-side pipe array holding members 9b and 9c of each pipe group 10 in the housing 2 (hereinafter referred to as “third housing space”). Thus, the resin material 123 in the injection pot 121 is filled exclusively in the first housing space, the second housing space, and the third housing space, whereby the gaps 7 (FIGS. 9A to 9C and 10) are formed. Further, the filing of the resin material is carried out while the jig 118 is being rotated, as described above. Therefore, with the centrifugal force caused by this rotation, the flow path 108 is formed in a cylindrical form as shown in FIG. 10.
Further, if the first and second housing spaces do not have an escape through which air goes out, when the filling of the resin material through the injection holes 115 is started, these spaces become completely closed spaces, and hence, the filling of the resin material becomes difficult. Therefore, as shown in FIGS. 9A to 9C, air vents 116 are provided on the side faces of the housing 102 so that the air vents communicate with the first and second housing spaces, respectively. In the example shown in FIG. 13, the air vents 116 are connected via pipes 125 with air vents 117 that are formed so as to communicate with the third housing space. Air squeezed out of the first and second housing spaces enters the third housing space, and then, is discharged through the inlet 104 or the outlet 105.
It should be noted that the function of the pipes 125 is not limited to this. Each capacity of the first and second housing spaces is smaller than the capacity of the third housing space, and the filling of the resin material into the first and second housing spaces ends earlier. Therefore, the pipes 125 also function for supplying excess resin material to the third housing space. In other words, in addition to the function of allowing the filing of the resin material to the first and second housing spaces to be performed smoothly, the pipes 125 also has the function of suppressing the waste of resin material, and the function of filling the third housing space with the resin material.
Thus, by injecting the resin material with use of the injection pot 121 shown in FIG. 14, the first sealing member 103a is formed in the first housing space, while the second sealing member 103b is formed in the second housing space. Further, in the third housing space, the third sealing member 103c is formed. Still further, since the resin material filled in the third housing space is subjected to the centrifugal force caused by the rotation of the jig 118, the flow path 108 is formed in the third housing space. Patent document 1: JP 2005-224301 A